Underfloor conduit system



' Selt 23. 1930 o. A. FREDERlcKsoN 4 UNDERFLOOR CONDUIT SYSTEM Filed April 9, 1928 ATTORNEY Patented sept. 23, 193e;

" UNITED 'STATES PATENT OFFI'Cf-E" OTTO ARTHUR FREDERICKSON, OF WETHERFIELD,

coNNEc'rIcUm, Assrelvon.,A BY

. ASSIGNMENTS, TO NATIONAL ELECTRIC PRODUCTS CORPORATION, OF NEW YORK,

UNDEBFLOOB OOND'O'IT SYSTEI Appntauon mea Api-u 9, 192s. 'serial 110.268,449.

My invention relates to'improvements in systems of -electrical distribution in which conduits or ducts are embedded in floor structures and branch connections are made from 5I such conduitsv through the floor. In some such systems the conduits have been exposed at thefloor surface and outlet openings have been formed in such conduits for branch connections, and in another such system the cont lo 4duits have been buried beneath the licor surface and openings have been-drilled through the floor and through the conduit for making branch connections through such open-v ings.r The drilling of the concrete lioor is Y 15 more or less expensive and the concrete'becomes injured to some extent surrounding the passages drilled therein, cementing around the passages being required in some instances to restore the ioor to proper con- 20 dition, and bushings are inserted through the passages and connected with the openmgs 1n the conduits. Another system embodies tubular inserts attached to the conduits in spaced relation prior to installation y 25 of the conduits in the floor structure, andthe llatter has been brought up substantially to the level of the outer 'ends of the inserts.

Where the conduits are provided with the spaced inserts a relatively large number of the latter are more or less wasted in use, be vcause more inserts are provided, than outlets are made from the conduits, and lsuch excess.

inserts increase the cost of the conduits and the installation of the system.v t

floor system of electrical distribution with means detaehably connectedv with the conduit that will provide pre-formed passages tors within the conduit, which. means in themselves are not inserts or bushings to be used for the branch connections. Y ,p Myf invention comprises novel detailsof 5o' Aimprovement be more fully herein- ,conduit therein;

The object of my invention is to provide aI conduit or duct that may be used in an underin theooring which means may be removed .-the conduit. The plugs are shown provided after` set -forth and then pointed'out in the claims. n

Reference is to be had to thev accompany-` ing drawings forming a part hereof, where- 1n I Fig. l illustrates my improved conduitand its parts separated; i

Fig. 2 is a cross section of conduit;

Fig. 3 is a longitudinal section througha floor structure, illustrating my improved my improved Fig. 4 is a sectional detail illustrating a' pre-formed passage in the flooring from which a plug has been removed to' permit. access to the'conduit; t Fig. 5 is a view similar lto Fig. 1, illustrat-v ing a modification; y FFig. 6 is a section through the conduitv of Fig. 7 is a sectional view illustrating an' opening formed in the conduit through the pre-formed passage in the Hoor, land'` Fig. 8 is Aa sectional detail illustrating-a bushmg within the passage in -the-iioor-and connected to the,conduit at the outlet openin therein. Y

imilar numerals of referenceindicate corresponding parts in the several views.

The` numeral 1 indicates a conduit which may be of any suitable or desired construction adapted to beembeddedin a concrete or analogous floor or. wall structure 2,. At '3 are p ugs detachably connected to a wall of the conduit, any desired number of the lugs being plrovided in suitabl spaced re ation along t e conduit.- Said p ugs are'shown in cylindrical form l having inner ends at 4 adapted to rest againstthe adjacent wall of .With passages or openings at5 through which screws 6 may be passed to engage threads in openings 7 in the'conduit for detachabl se# curing'the plugs to the latter. In`the germ shown in Figs. .1, 2 and 3,the plug is solid except for the passage. 5 anda recess 5n at" the outer end to countersink-the screw' head, and the conduit is weakened or cutat 8, with an uncut portion at 8*, providing a knoclzout at 9 retained by" the portion 8*, n

The knockout has a threaded opening 7 for screw 6. When the parts are assembled, as

shown in Figs. 2 and 3, the plug will be secured to the knockout 9 by screw 6, and preferably the base of the plug will be wider than the knockout to rest upon the top wall of the conduit, whereby the plug is detachably secured to the conduit. A ferrule or cap 10 may be secured on the plug friction tight and may have an opening at 10so to admit a screwdriver to operate screw 6. Said plugs ma be of wood or other suitable material, an may be provided with reduced outer ends, at 11, to receive the flanges 10b of the ferrules, providing smooth outer surfaces along the lugs.

In the orm shown in Figs. 5 and 6 the plugs are hollow, in cup-like form, with their inner ends or bases secured to the conduit by the screws 6, and the ferrules or caps 10 are shown provided with external threads at 10a along their flanges 10 to engage internal threads 3 at the outer ends of the plugs, (Fig. 6). The ferrules or caps 10c` may be removed from the plugs to permit access of a screwdriver to the screws 6 to attach the plugs to the conduit and for removal of the plugs therefrom. The plugs or cups may be made of relatively cheap material so -that the cost of the completed conduit with the plugs or cu s will be relatively low.

The plug of igs. 1 and 2 may be used on the conduit of Figs. 5 and 6, and the plug of Figs. 5 and G may be used on the conduit of Figs. 1 and 2. When a plug is to be removed from the conduit a screw driver may be used for removal of the screw -6 from the conduit, whereby the plug may be lifted from the conduit, providing a pre-formed passage 2** in the concrete, throu h which branch connections may be made rom conductors within the conduit.

The conduit may be embedded in a floor or wall structure in any well known way, such as b resting the conduit upon a rough slab of t e iioor or on suitable seats, with the plugs 3 fitted to the conduit, and the ioor'or wall material will be laid so as to be substantially flush with the tops of the lugs, the concrete or cement being properly aid around the plugs with their ferrules or caps exposed. When it is desired to make a branch connection to a conductor in the conduit the corresponding screw 6 will be unscrewed from the conduit, thereby releasing the plug therefrom, and the latter may be withdrawn from the pre-formed passagey 2Il in the floor, which passage will open through the floor or wall surface, indicated 1n Figs. 4 and 7. The opening 7 in the conduit will preferably be in the axial center of the passage 2a in the floor or wall 2. In the form shown in Figs. 1, 2 and 3. the knockout 9 will'be removed, and the edges of the opening 12, (formed in the conduit by the removal of the knockout), may be smoothed by a suitable tool. In the form shown in Figs. 5 and 6, after the plug 3 has been removed an outlet opening 12a may be drilled in the conduit through the passage 2a, as indicated in Fig. 7, the open'- ing 7 in the conduit serving as a pilot for the drill or cutter and to indicate the center of the passage 2a. After the openingl has been formed in the conduit a bushing or tting 13 may be passed through the passage 2a in the floor or wall and connected with the opening in the conduit to secure the bushing thereto in any desired way, such as by upsetting the metal at the inner end of the bushing, as indicated at 14 in Fig.

8, to securely attach the bushing to the conduit.

In accordance withmy improvement conduits or ducts may be installed in any de 85 sired connected relation within ioor and wall structures with pre-formed passages 2EL in the latter produced by the presence of the plugs 3 in the concrete, permitting any of the desired plugs to be removed so that a 9o corresponding opening may be formed in the conduit for making branch electrical connections without disturbing the concrete or any of the other plugs along the conduit until access to the conduit is required at any other position. Since the plugs 3 may be made of material much cheaper than finished bushings 13 it will be apparent that the -cost of the conduits with their plugs attached will be cheaper than with conduits to which permanent inserts are attached prior to installation in the floor or wall, since such of said more costly permanent inserts as are not used for branch connections and which are permanently installed in the floor or wall entail increased cost, as only such bushings 13 as are required for a particular outlet'or branch connection are required to be fitted to a conduit in my improved electrical distribution system.

Having now described my inventionfwhat I claim is 1. A conduit for a system of electrical disl tribution having spaced plugs, and screws passing through openings in the plugs for detachably securing said plugs to the conduit, said plugs projecting from the exterior of the conduit in position to provide preformed passages in the structure in which the conduit and the plugs are embedded, said passages affording access to theyconduit for the removal of conduit material and also affordin I an opening to and through the conduit a ter the conduit material has been removed for the assage of wires from the con- -duit throu ht e passages formed by the removal oft e plugs.

2. A conduit for a system of electrical distribution provided with spaced plugs thereon, said plugs having bases against the 1:0

conduit, and screws detachably connecting the plu s with the conduit, said screws having their heads within the plugs and their shanks passing through the plugs, the plugs projecting from the conduit in position to provide pre-formed passages in a structure in which the conduit and the plugs are embedded, said passages aiording access to the conduit for the removal of conduit material and also affording an opening to and through the conduit after the conduit material has been removed for the passage of wires from the conduit through the passages formed by the removal of the plugs.

8. A conduit provided with spaced threaded openings in a wall, plugs against said wall having openings registering withthe openings 1n the conduit, and screws passing through the openings in the plugs and engaging the threads in the openings in the conduit for detachabl connecting the plugs with the conduit, sai screws providing for the removal of a plug so that the underlying conduit material may be accessible for removal whereupon after removal of such conduit material a passage is provided through the wall of the conduit.

4. A conduit rovided with a knockout, a plug upon the ockout and means to secure the plug to the knockout. l

5. A conduit as set forth in claim 4 in which the base of the plug is wider than the knockout and rests against the conduit.

6. A conduit' provided with a knockout having a threaded opening, a plug upon the knockout, anda screw extending from the plug and engaging the threads in said opening for detachably connecting the plug with the knockout. l

7. A conduit as set forth in claim 6 in which the base of the plug is wider than the knockout and rests against the conduit.

8. A concealed electrical distribution system for poured buildin structures comprising a poured slab, a con uit wholly embedded in the slab at a substantial distance from the slab surfaces, plugs removably attached to a wall of the conduit, and extending from the wall to a surface of the slab, said plugs being attached to the conduit by screws which are independent. of the plugs and which pass through an opening in said plugs and engage threaded a erturs in the conduit, the plugs being so s aped as to facilitate their removal, intact fom the structure after the material of the slab has set,

"9. A concealed electrical distribution system for poured buildin structures com ris- I ing a poured slab, a con uit wholly embe ded in the slab at a substantial distance from the slab surfaces, plugs removably attached to a wall ofthe conduit, and extending from the wall to a surface of the slab, said plu being attached` to the conduit by screws w ich are independent of the plugs and which pass through an opening in said plugs and engage threaded apertures in the conduit, the plugs being so shaped as to facilitate their removal,

intact from the structure after the material of the slab has set and ferrules surrounding the ends of the plugs flush with the slab surm face.

OTTO ARTHUR FREDERICKSON. 

